DS-TE應用MPLS VPN網(wǎng)絡解決時延問題的研究
發(fā)布時間：2018-12-12 13:09
【摘要】：多協(xié)議標簽交換核心之處就是標簽概念的引入和應用。多協(xié)議標簽交換主要有CE、PE、P三部分組成，CE也叫用戶邊緣路由，主要為用戶接入VPN業(yè)務，PE也叫服務提供商邊緣路由，它與CE直接相連，具有MPLS網(wǎng)絡中LER的功能，同時還為每個用戶創(chuàng)建一個虛擬路由轉(zhuǎn)發(fā)表，以此實現(xiàn)多個VPN用戶的隔離和VPN業(yè)務標簽的分發(fā)。P也叫骨干網(wǎng)核心路由，它具有MPLS網(wǎng)絡中LSR的功能，完成快速轉(zhuǎn)發(fā)和控制任務。 DS-TE技術(shù)是區(qū)分服務模型和流量工程模型的集合，在區(qū)分服務模型中數(shù)據(jù)分組根據(jù)業(yè)務等級分為不同的優(yōu)先級，體現(xiàn)在封裝中的TOS字段，由6位二進制數(shù)組成，共分為12個級別，最高級別屬于網(wǎng)絡控制類；最低級別屬于盡可能服務類。當MPLSVPN接收到具有區(qū)分服務等級的數(shù)據(jù)包時PE(LER)會將PHB映射成標簽中的EXP字段，將12個優(yōu)先級轉(zhuǎn)化成8個優(yōu)先級，然后根據(jù)不同的優(yōu)先級選擇不同LSP資源。流量工程模型在MPLS VPN中的作用是防止過多同類型或同優(yōu)先級的轉(zhuǎn)發(fā)等價類占用同一個或同幾個LSP資源而造成其他一些帶寬資源被浪費，MPLS TE所需要使用的功能部件大致由四個部分組成：分組轉(zhuǎn)發(fā)、信息分發(fā)、路徑計算和信令部件。所以，流量工程很大程度上可以減少VPN網(wǎng)絡中的擁塞的情況發(fā)生。因此，DS-TE技術(shù)是一種既滿足了用戶的通信需求又能為運營商避免資源浪費情況的雙重保障技術(shù)。 BH算法出發(fā)點是解決帶寬浪費的問題，所以算法的搶占原則和代價公式都是以帶寬的利用率為主。當前的計算機通信網(wǎng)絡由于光線通信的發(fā)展已經(jīng)擁有非常豐富的帶寬資源，國內(nèi)的各大運營商也陸續(xù)開始對帶寬業(yè)務降價促銷。所以企業(yè)用戶的可用的帶寬資源已經(jīng)不再是限制通信服務質(zhì)量的瓶頸。BH-PREPT算法在避免級聯(lián)搶占方面有較好的性能，缺點是過多的關(guān)注了由于搶占LSP造成帶寬浪費的代價而使算法的復雜度和對設備要求提高很多。 作者提出改進的BH-PREPT算法即LH-PREPT算法。該算法有著兼顧避免級聯(lián)搶占和搶占優(yōu)先級代價最小的特點，在通信網(wǎng)絡性能方面主要體現(xiàn)在VPN用戶的主要業(yè)務的時延有所減少。作者根據(jù)當前的VPN業(yè)務對通信網(wǎng)絡性能的需求對總代價計算公式H(l)進行了簡單的修正，將y (l)修改成y2(l)以增加優(yōu)先級搶占代價在總代價中的比重。為了兼顧資源的有效利用和時延特性的提高，，算法在帶寬資源和LSP資源條件允許的情況下，用戶的通信分組將直接搶占當前的LSP資源以減少時延；當通信資源有限或LSP無法滿足用戶的通信需求時，算法會將當前的LSP隧道捆綁使用以增加LSP資源的利用率。最后作者使用OPNET仿真了兩種算法的通信場景，在兩個場景中的通信節(jié)點分別采用LH-PREPT算法策略和BH-PREPT算法策略，然后作者對實驗結(jié)果進行了對比和分析，最后得出了新算法在減少通信時延方面有較好的性能結(jié)論。
[Abstract]:The core of multiprotocol label switching is the introduction and application of label concept. Multi-protocol label switching consists of three parts of CE,PE,P, CE is also called user edge routing, mainly for users to access VPN services, PE is also called service provider edge routing, it is directly connected with CE and has the function of LER in MPLS network. At the same time, a virtual route forwarding table is created for each user to isolate multiple VPN users and distribute VPN service labels. P is also called core routing of backbone network. It has the function of LSR in MPLS network and completes fast forwarding and control tasks. DS-TE technology is a collection of differentiated service model and traffic engineering model. In the differentiated service model, the data grouping is divided into different priority according to the service level, which is embodied in the encapsulation of the TOS field, which is composed of six binary digits. It is divided into 12 levels, the highest level belongs to the network control class; The lowest level belongs to the service class as much as possible. When MPLSVPN receives packet with differentiated service level, PE (LER) maps PHB to EXP field in label, converts 12 priority into 8 priority, and then selects different LSP resource according to different priority. The function of traffic engineering model in MPLS VPN is to prevent too many forwarding equivalents of the same type or priority from occupying the same or several LSP resources and causing other bandwidth resources to be wasted. The functional components that MPLS TE needs to use consist of four parts: packet forwarding, information distribution, path calculation and signaling. Therefore, traffic engineering can greatly reduce congestion in VPN networks. Therefore, DS-TE technology is a kind of dual safeguard technology which can not only meet the communication needs of users but also avoid the waste of resources for operators. The starting point of BH algorithm is to solve the problem of bandwidth waste, so the preemption principle and cost formula of the algorithm are mainly based on the utilization of bandwidth. Due to the development of optical communication, the current computer communication network has a very rich bandwidth resources, and the major domestic operators have started to reduce the price of bandwidth services. Therefore, the available bandwidth resources of enterprise users are no longer the bottleneck limiting the quality of communication service. BH-PREPT algorithm has better performance in avoiding cascading preemption. The drawback is that too much attention is paid to the cost of bandwidth waste caused by preemption of LSP, which makes the complexity of the algorithm and the requirement of the device much higher. The author proposes an improved BH-PREPT algorithm, that is, LH-PREPT algorithm. The algorithm has the advantages of avoiding cascade preemption and preemptive priority cost minimization. The performance of communication network is mainly reflected in the reduction of delay of the main services of VPN users. According to the current demand of VPN services for communication network performance, the author modifies the total cost calculation formula (H (l) and modifies the y (l) to y2 (l) to increase the proportion of priority preemptive cost in the total cost. In order to take into account the efficient utilization of resources and the improvement of delay characteristics, when bandwidth resources and LSP resource conditions are allowed, the user's communication packets will directly preempt the current LSP resources to reduce the delay. When the communication resource is limited or the LSP can not meet the user's communication demand, the algorithm will bundle the current LSP tunnel to increase the utilization of the LSP resource. Finally, the author simulates the communication scene of the two algorithms by using OPNET. The communication nodes in the two scenarios adopt the LH-PREPT algorithm strategy and the BH-PREPT algorithm strategy respectively. Then the author compares and analyzes the experimental results. Finally, it is concluded that the new algorithm has good performance in reducing communication delay.
【學位授予單位】：吉林大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TP393.1
本文編號：2374618
[Abstract]:The core of multiprotocol label switching is the introduction and application of label concept. Multi-protocol label switching consists of three parts of CE,PE,P, CE is also called user edge routing, mainly for users to access VPN services, PE is also called service provider edge routing, it is directly connected with CE and has the function of LER in MPLS network. At the same time, a virtual route forwarding table is created for each user to isolate multiple VPN users and distribute VPN service labels. P is also called core routing of backbone network. It has the function of LSR in MPLS network and completes fast forwarding and control tasks. DS-TE technology is a collection of differentiated service model and traffic engineering model. In the differentiated service model, the data grouping is divided into different priority according to the service level, which is embodied in the encapsulation of the TOS field, which is composed of six binary digits. It is divided into 12 levels, the highest level belongs to the network control class; The lowest level belongs to the service class as much as possible. When MPLSVPN receives packet with differentiated service level, PE (LER) maps PHB to EXP field in label, converts 12 priority into 8 priority, and then selects different LSP resource according to different priority. The function of traffic engineering model in MPLS VPN is to prevent too many forwarding equivalents of the same type or priority from occupying the same or several LSP resources and causing other bandwidth resources to be wasted. The functional components that MPLS TE needs to use consist of four parts: packet forwarding, information distribution, path calculation and signaling. Therefore, traffic engineering can greatly reduce congestion in VPN networks. Therefore, DS-TE technology is a kind of dual safeguard technology which can not only meet the communication needs of users but also avoid the waste of resources for operators. The starting point of BH algorithm is to solve the problem of bandwidth waste, so the preemption principle and cost formula of the algorithm are mainly based on the utilization of bandwidth. Due to the development of optical communication, the current computer communication network has a very rich bandwidth resources, and the major domestic operators have started to reduce the price of bandwidth services. Therefore, the available bandwidth resources of enterprise users are no longer the bottleneck limiting the quality of communication service. BH-PREPT algorithm has better performance in avoiding cascading preemption. The drawback is that too much attention is paid to the cost of bandwidth waste caused by preemption of LSP, which makes the complexity of the algorithm and the requirement of the device much higher. The author proposes an improved BH-PREPT algorithm, that is, LH-PREPT algorithm. The algorithm has the advantages of avoiding cascade preemption and preemptive priority cost minimization. The performance of communication network is mainly reflected in the reduction of delay of the main services of VPN users. According to the current demand of VPN services for communication network performance, the author modifies the total cost calculation formula (H (l) and modifies the y (l) to y2 (l) to increase the proportion of priority preemptive cost in the total cost. In order to take into account the efficient utilization of resources and the improvement of delay characteristics, when bandwidth resources and LSP resource conditions are allowed, the user's communication packets will directly preempt the current LSP resources to reduce the delay. When the communication resource is limited or the LSP can not meet the user's communication demand, the algorithm will bundle the current LSP tunnel to increase the utilization of the LSP resource. Finally, the author simulates the communication scene of the two algorithms by using OPNET. The communication nodes in the two scenarios adopt the LH-PREPT algorithm strategy and the BH-PREPT algorithm strategy respectively. Then the author compares and analyzes the experimental results. Finally, it is concluded that the new algorithm has good performance in reducing communication delay.
【學位授予單位】：吉林大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TP393.1
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